Rejector-blade wear-compensatingring, for discharge of rotary beater mill



Jan. 18, 1949. E. H. SMITH ETAL 5 REJEGTOR-BLADE WEAR-COMPENSATING-RING. A FOR DISCHARGE OF ROTARY BEATER MILL Filed Jan. 31, 1947 2 Sheets-Sheet l Jan. 18, 1949. E. H. SMITH ETAL 2,459,248

REJECTOR-BLADE WEAR-COMPENSATING-RING, FOR DISCHARGE OF ROTARY HEATER MILL Filed Jan. 31, 1947 v 2 Sheets-Sheet 2 /a i 29 /a 29 I ,a g l, M 6 33 /5 A? :4 /2

2 vs gfi /4 L; Fig. 7 20 Fig.6

ER/c H. JM/TH 05cm? 14. c/OHNJO/V Patented Jan. 18, 1949 RING, HEATER FOR DISCHARGE OF ROTARY MILL Eric H. Smlth'and Oscar A. Johnson, Worcester, Mass., asslgnors to Riley Stoker Corporation, Worcester, Mass a corporation oi Massachusetts Application January 31, 1947, Serial No. 725,440

3 Claims.

This invention relates to pulverizing apparatus, and more particularly to apparatus of the type having beaters which revolve about a central outlet leading to a fan chamber.

In a machine of this type the heaters serve to .pulverlze material which travels through the machine on a current of air produced by a fan revolving in the fan chamber, and the fine particles of material are carried through the outlet by the air current. In order to prevent the escape of coarse particles it is known practice to provide blades which revolve adjacent the outlet and across the path of the material as it approaches the outlet. It is intended that these socalled "rejector" blades shall separate the coarse particles from the issuing stream of pulverized material and air, and return these coarse particles for further pulverization by the beaters. It has been found however that after a considerable period of service a greater proportion of coarse particles escape from the pulverizing zone. and eventually it becomes necessary to take the machine out of service and replace various parts, such as the rejector blades and the revoluble beaters, which have become worn by the abrasive action of the material.

It is one object of the invention to provide a pulverizing apparatus having an improved construction for the central outlet-forming ring and associated parts whereby the ring may be readily adjusted to maintain delivery of a product of the requisite fineness throughout long periods of service.

It is a further object of the invention to provide, in a pulverizer of the type having rejector blades revoluble adjacent a central outlet, a new and advantageous construction including a ring forming the said outlet and manually operable means for adjusting the ring axially to compensate for wear of the rejector blades.

With these and other objects in view. as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is a section through a pulverizing apparatus, the section being taken on the line ll of Fig.

Fig. 2 is a fragmentary section taken on the line 22 of Fig. 1;

Fig. 3 is a detail of an outlet ring forming a part of the apparatus;

Fig. 4 is a fragmentary elevation taken as indicated by the line 44 of .Fig. 1;

Fig. 5 is an enlarged fragmentary view in sec.- tion taken on the line 55 of Fig. 1;

v Fig. 6 is a fragmentary section taken on the line i-S of Fig. 5;

Fig. 7 is a view similar to Fig. 5 but showing certain parts adjusted to compensate for wear;

and

Fig. 8 is a fragmentary section taken on the line 8-8 oi! Fig. 7.

The drawings show a pulverizing apparatus of the general type disclosed in the United States patent to Andrews No. 1,840,380, granted January 12, 1932, to which reference may be had for a more complete description of certain portions of the machine. The embodiment illustrated herein comprises a casing IO'shaped to provide a pulverizing chamber I l and a fan chamber I2 separated by an upright partition including a wall I! having a central circular opening I5. For convenience in assembly. and to permit access to the interior of the machine, the casing I0 is formed in two parts which are separable along a horizontal plane passing through the center of the opening II. The fan chamber I2 is provided with the usual tangentially positioned outlet IS. A horizontal rotatable shaft l8 extends centrally through the opening 15 and supports a vertical rotor disk l8 within the pulverizing chamber II. On the side of the diskLllfl'Effiiri'gtthe wall 14 there are mounted {revoliiblepulverizing elements or heaters 20 which-cooperate with stationary pegs 2| in pulverizing material. The pegsjjl are provided with flanged bases, and they are supported by an annular plate 23 suitably secured to the wall II. The plate 23 surrounds a ring 24 which is attached to the wall I in registration with the opening l5. An inner ring 25 ismounted within the opening l5 and within the ring 24 to define a central outlet opening 21 through which the pulverized material may travel in a current of air from the pulverizing chamber I I into the fan chamber l2. As shown in Fig. 3, the ring 26 is preferably made in two separable parts to facilitate assembly.

It is important to prevent coarse particles of material from passing through the opening 21. For this purpose a hub 29 is mounted on the shaft l8 and to this hub there are secured a plurality of rejector blades 30 which extend outwardly across the opening 21. The outer ends of these blades overlap the entrance side of the ring 26, in close proximity thereto. As best shown in Fig. 6, each blade 30 is of U-shape in cross section to provide a groove along its front surface, so that the rapidly revolving blades will scoop coarse particles of material out of the air stream approaching the outlet opening 21 and throw these particles back into the chamber H for further pulverization.

The coarse particles of material have a much greater weight in proportion to their surface area than the fine particles. Consequently the coarse particles are more influenced by centrifugal forces and less influenced by the inwardly flowing air currents. As a result, the coarse particles tend to remain in the outer portion of the pulverizing zone until they have been reduced in size, and such coarse particles as do approach the outlet opening 21 will usually travel close to the outer ends of the blades 30 and the adjacent rapidly revolving blades 30 and thrown back into the pulverizing zone H for further pulverization. Since most of these particles travel close to the surface of the ring 26, the blades 30 eventually become worn at their outer corners adjacent the ring. Such wear tends to open up a wide gap between the rejector blades 30 and the ring 26, I

and. if this is permitted to occur many coarse particles will pass through the gap and escape with the finished product. Consequently, with prior constructions it will be necessary to shut down the machine and replace the worn rejector blades with new blades. With the present in vention, on the other hand, at the slightest indisurface of the ring 26. This causes the wear on f the blades to be concentrated on their outer corners at the side toward the ring 26, thereby forming a space through which coarse particles tend to escape past the blades and through the opening 21.

The present invention provides a mechanism whereby the ring 26 may be moved in the axial direction toward the blades 30 to take up any clearance resulting from wear on the blades. This mechanism is preferably operable manually without the necessity for opening the casing It] or even shutting down the machine. In the construction illustrated the ring 26 is'provided with two diametrically opposite recesses 32 located in the outer surface of the ring and in substantially the horizontal axial plane. Each recess is formed with parallel vertical side surfaces, and it is slightly elongated in the vertical direction. Within each recess 32 there is located a cam 33 in the form of a circular disk with its periphery substantially in contact with the side surfaces of the recess. Each disk 33 is eccentrically mounted on the inner end of a horizontal rod 35 which extends outwardly between the partition wall l4 and the plate 23. In order to prevent the rods 35 from being clamped laterally against the wall 14, spacer plates 36 (Fig. 2) are provided above and beneath therods between the wall I4 and the flanged bases of the pegs 2|, thereby forming radially extending openings for the reception of I the rods. On the outer end of each rod 35 there is mounted a handle 38 whereby the rod may be turned about its axis. Each handle 38 is provided with a bolt 39 which serves to secure the handle in a desired position to a slotted segment 40 mounted on the casing ill.

The operation of the invention will now be apparent from the above disclosure. Frangible material, for example bituminous coal, will be pulverized in the pulverizing zone II by the action of the revolving heaters 20 and the stationary pegs 2 I. In known manner, a revolving fan within the fan chamber l2 will produce an air current through the pulverizing chamber H, thence through the opening 21 into the fan chamber, and through the outlet l6. This air current will entrain the finely pulverized particles of material and carry them along in suspension. The coarse particles, aided by centrifugal force, will resist such entrainment. Some particles which are somewhat coarser than is desired in the final product will approach the opening 21, but they will usually travel at a lower speed than the fine particles. Accordingly these coarser particles will be scoopedout of the air current by the cation of increased coarseness in the product, the operator will simply turn the rods 35 and the cams 33 by means of the handles 38, thereby moving the ring 26 axially toward the worn blades. Figs. '7 and 8 indicate the extent to which the rejector blades may become worn without increasing the initial clearance, provided the ring 26 is adjusted occasionally as wear takes place. This makes it possible to operate the machine for long continuous periods before the rejector blades become so worn as to require replacement. Furthermore, with proper clearance maintained between the ring and the rejector blades, wear on the heaters and pegs will have little effect on the fineness of the product leaving the machine.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In a pulveriz ing apparatus of the type having a casing divided internally by a partition into a pulverizing zone and a fan chamber, the partition having an opening therethrough in which a ring is supported to define an outlet opening for the escape of pulverized material from the pulverizing I zone to the fan chamber, and revoluble rejector blades with their outer'ends overlapping the entrance side of the ring to prevent the escape of coarse particles of material therethrough, an improved mechanism for counteracting the effect of rejector blade wear comprising two rods extending substantially radially outward from oppositesides of the ring, handles connected to the outer ends of the rods to turn them about their axes, and means connecting the inner ends of the rods to the ring in such a manner as to move the ring axially in the partition opening as the rods are turned.

2. Apparatus as set forth in claim 1, in which the ring is formed with two recesses in its outer:

surface adjacent the inner ends of the respective rods, and a cam is provided on the inner end of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 619,353 Schutz Feb. 14, 1899' 1,566,546 Lauritzen Dec. 22, 1925 1,603,520 Crites Oct. 19, 1926 1,840,380 Andrews Jan. 12, 1932 

